title: A protein from Aloe vera that inhibits the cleavage of human fibrin(ogen) by plasmin.
abstract: A protease inhibitor protein with the molecular mass of 11,804.931 Da (analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) was isolated from Aloe vera leaf gel and designated as AVPI-12. The isoelectric point of the protein is about 7.43. The first ten amino acid sequence from the N-terminal was found to be R-D-W-A-E-P-N-D-G-Y, which did not match other protease inhibitors in database searches and other publications, indicating AVPI-12 is a novel protease inhibitor. The band protein of AVPI-12 migrated further on nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) than reducing SDS-PAGE. This result indicated that the molecule of AVPI-12 did not contain interchain disulfide bonds, but appeared to have intrachain disulfide bonds instead. AVPI-12 strongly resisted digestion by the serine proteases human plasmin and bovine trypsin. The protein could protect the γ-subunit of human fibrinogen from plasmin and trypsin digestion, similar to the natural plasma serine protease inhibitor α2-macroglobulin. The protein also could protect the γ-subunit of fibrinogen from the cysteine protease papain. AVPI-12 also exhibited dose-dependent inhibition of the fibrinogenolytic activity of plasmin, similar to α2-macroglobulin. The fibrinolytic inhibitory activity of AVPI-12 and the small-angle X-ray scattering showed that the protein could protect human fibrin clot from complete degradation by plasmin. The inhibition of the fibrinogenolytic and fibrinolytic activities of plasmin by AVPI-12 suggests that the inhibitor has potential for use in antifibrinolytic treatment.
authors.affiliation: School of Biochemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand. jaruwan_siritape@yahoo.com
authors.forename: Jaruwan
authors.initials: J
authors.lastname: Siritapetawee
authors.forename: Punchapat
authors.initials: P
authors.lastname: Sojikul
authors.forename: Siriwat
authors.initials: S
authors.lastname: Soontaranon
authors.forename: Wanwisa
authors.initials: W
authors.lastname: Limphirat
authors.forename: Sompong
authors.initials: S
authors.lastname: Thammasirirak
mesh_terms: D000504:Aloe / Q000378:metabolism*; D005340:Fibrinogen / Q000737:chemistry*; D005341:Fibrinolysin / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011480:Protease Inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D010940:Plant Proteins; D011480:Protease Inhibitors; D005340:Fibrinogen; D005341:Fibrinolysin